Lead-tin alloy plating



.pat the; same time prgduc Patented Jan. 25, 1949 35 .594? LEAD-TIN Arthur Dn BoSe, QucIiG aHQJQ n. L m

of Ohio No llrayving Application February 9 gfl.6,

he llai shaw This invention relateswto lead-tin alloy plating and more specifically to a method of and means for causing preferential depg it9n; of tin whereby the solution may have a smaller concentration :i-with respect to tin" thannormally. would bf'required for producing a co-deposit-..coritainingi a given percentage .of tin.

We are aware thatpriorto our' invention deposits of lead and tin have been made. licls ord g y. 69 n t claimed-t l-aeratin t irbrv-e EQbYiQ SLPQW Ver lh i aeletine solution containing only a small concentration of tin can bec'au'sed to deposit relatively more tin thanlead as compared to previous soluti deposits suitable for prtect'ivtbatingsr ardennite advantage will; begainedjn-that the dragout loss of the relatively expensive tinwill be 'redued'. i I I I We have now discovered a class 0f addition agents which ay be a'ddedQtQ' up crafted? sulfamate solutions oflead-tin ele l'ytescofiaining -'partsof"tiri oElesspeF-"IUW arts'of fead by weight and which will cause preferential deposition of tin from such solutions. The class of addition agents referred to consists of the mono-, di-, and tri-hydroxy benzenes, the mono-, diand tri-hydroxy diphenyls and the chloro, bromo, amino, methyl, ethyl, propyl and isopropyl substitution products of the above named addition agents wherein the named substituents are connected to ring carbon. Specific examples of the class which have been found to produce preferential deposition of tin are resorcinol, catechol, hydroquinone, pyrogallol, phloroglucinol, phenol, cresol, p-amino phenol, 2,4,5,6 trichlorophenol, o-amyl phenol, o-bromo phenol, 2,4-dihydroxydiphenyl.

We have found that addition agents of the above group are efiective in commercial plating solutions of the fiuoborate and sulfamate types. The corresponding hydroxy naphthalenes are efiective in the higher concentrations of tin but where the tin calculated as S11 is less than 5 parts .18111 additiofilaeentloilithenclass" on- -tivescoatingasjfieneihafteiiihdicated;QL'Pt .sqlution' coinpositionsti013 theseltyiieslo a1 i; jsistineioflmono di-, and -tri-;hy-

droxy benzenesaandidibhenylsland iithir Zielildro, b'riimol "1 amino,

methyl, ethyl Jptcmyl. .-,.andii;1isoprdpyl derivatives; lwherein-Ithe l substituents are onwringi carbon 1 Landhiixtfirs of a..plural it .tliereof J 0.2 to 5 Water s Remainder Suljamdte solution The following table showing specific examples Ti to 250 to 1.5 0 to 1.5

from actual practice will serve to illustrate the invention:

Grams per liter of solution except as noted (remainder water) Example No 1 2 3 4 5 Lead Fluoborate (Pb Content)--. Tin Fluoborate (Sn Content) 7 5 Fluoboric Acid 10 Lead Sulfamate (Pb Content)... Tin Sulfamate (Sn Content) Suli'amic Acid (To give pH of) Glue .1

3,4 dihydroxydipheuyl Orthobromophenol 'linindeposit Tin in deposit in absence of special addition agent 1 Powdery deposit. Not suitable ior use as a protective coating.

This application is a continuation-in-partoi f our co-pending application Serial No. 569,262,

filed December 21, 194%, which has become aban per liter of glue.

doned.

Having thusfde'scribed our invention, what we claim is:

1. An aqueous, acid lead-tin plating solution es- =sentially consisting of from 100 to 400 grams per liter combined concentration of lead and tin ions, negative ions of the classconsisting of fluoborate and sulfamate and an addition agent effective to "cause increased deposition of tin in proportion to lead deposited, the concentration of tin ions being from 1% to 5% of the combined weight of lead and tin ions, and said addition agent being present to the extent of from 0.2 to 5 grams per liter and being selected from the class consisting ofresorcinol, catechol, hydroquinone, py-

rogallol, phloroglucinol, phenol, naphthol, cresol, 3,4 dihydroxydiphenyl, orthobromophenol, pamino phenol and o-amyl phenol. a

2. The invention according to claim 1 wherein said additionagent is resorcinol.

3. The invention according to claim 1.wherein.

said addition agent is phenol.

4. The invention according to claim 1 wherein said addition agent is hydroquinone.

5. The invention according to claim 1 wherein said solution also contains from 0.2 to 1.5 grams ARTHUR H. DU ROSE. JOHN D. LITTLE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 12,301 Betts Jan. 3, 1905 2,318,592 Cupery May 11, 1943 FOREIGN PATENTS 45 Number Country Date 329,346 Great Britain May 16, 1930 OTHER REFERENCES Transactions of Electrochemical Society, vol. 76, pp. 371-382 (1939). Transactions of Electrochemical Society, vol. 40, pp. 296-299 (1921).

Chemical Abstracts, vol. 38, p. 2571 (1944). 

